[tip: x86/iopl] selftests/x86/ioperm: Extend testing so the shared bitmap is exercised

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the x86/iopl branch of tip:

Commit-ID:     0907a09c2e52210a67a9616427ea71f14b37e826
Gitweb:        https://git.kernel.org/tip/0907a09c2e52210a67a9616427ea71f14b37e826
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Mon, 11 Nov 2019 23:03:26 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Sat, 16 Nov 2019 11:24:04 +01:00

selftests/x86/ioperm: Extend testing so the shared bitmap is exercised

Add code to the fork path which forces the shared bitmap to be duplicated
and the reference count to be dropped. Verify that the child modifications
did not affect the parent.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

---
 tools/testing/selftests/x86/ioperm.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/x86/ioperm.c b/tools/testing/selftests/x86/ioperm.c
index 01de41c..57ec5e9 100644
--- a/tools/testing/selftests/x86/ioperm.c
+++ b/tools/testing/selftests/x86/ioperm.c
@@ -131,6 +131,17 @@ int main(void)
 		printf("[RUN]\tchild: check that we inherited permissions\n");
 		expect_ok(0x80);
 		expect_gp(0xed);
+		printf("[RUN]\tchild: Extend permissions to 0x81\n");
+		if (ioperm(0x81, 1, 1) != 0) {
+			printf("[FAIL]\tioperm(0x81, 1, 1) failed (%d)", errno);
+			return 1;
+		}
+		printf("[RUN]\tchild: Drop permissions to 0x80\n");
+		if (ioperm(0x80, 1, 0) != 0) {
+			printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
+			return 1;
+		}
+		expect_gp(0x80);
 		return 0;
 	} else {
 		int status;
@@ -146,8 +157,11 @@ int main(void)
 		}
 	}
 
-	/* Test the capability checks. */
+	/* Verify that the child dropping 0x80 did not affect the parent */
+	printf("\tVerify that unsharing the bitmap worked\n");
+	expect_ok(0x80);
 
+	/* Test the capability checks. */
 	printf("\tDrop privileges\n");
 	if (setresuid(1, 1, 1) != 0) {
 		printf("[WARN]\tDropping privileges failed\n");